Since the shopping cart was invented, retailers have struggled to minimize Bottom-of-the Basket (BoB) losses which occur when costumer inadvertently, or purposefully, fail to pay for items placed on the bottom rack of a shopping cart. In principle, the cashier should verify that all items in the cart and BoB have been accounted for in the purchase. In practice, however, millions of dollars of merchandise are lost every year.
Many solutions to the problem have been attempted, but none of them have satisfactorily solved it. One solution is to place mirrors on the opposite side of the checkout lane, thereby providing the cashier a view of the bottom-of-the-basket for visual inspection. Another solution is to install video cameras aimed at the bottom-of-the-basket in the lane and a display to show the cashier live video of the bottom trays of carts as they pass by. Both these methods require the cashier to continuously monitor the view of the cart in addition to their other responsibilities. Both these methods fail, however, because the cashiers tend to ignore the extra stimulus over time.
Other solutions involve putting special markers on the cart to detect the presence of the cart, and then probe the cart with a beam at the appropriate time to sense whether there is something in the bottom-of-the-basket or not. If something is detected, the cashier is alerted with an audible or visual signal. These systems, although an improvement over the passive systems described above, still fail to prevent BoB loss because the systems are not very accurate and tend to generate too many false alarms. Cashiers tend to lose confidence in the system which they then ignore.
There is therefore a need for a BoB item detection system that can accurately detect the presence of merchandise on a cart with very few false positives and potentially lock the cash register in such a way that the cashier cannot complete the transaction without processing the BoB item.